Abstract

“The Perfect Island” explores the second principle mentioned in chapter 11, that is, the principle that for whatever exists solely in the understanding, something greater than it can be conceived. There are at least five versions of that principle, of varying strength. Anselm’s argument relies on the weakest of the five. Gaunilo invoked his “lost island” counterexample in an attempt to demonstrate that an argument structurally identical to Anselm’s would “prove” the existence of the greatest conceivable island, thus exposing the absurdity of Anselm’s argument. But Anselm’s argument relies only on the weakest version of the second principle, whereas Gaunilo’s argument requires one of the stronger versions. This chapter presents a model in which the weakest version is true while the other four versions are false. Gaunilo’s argument is thus not a successful counterexample.